fix(buyer-tasks): pass status + email_error into SendPoModal stub

The SendPoModal renders its 'Resend' label and inline failure
banner from purchaseOrder.status / email_error, but the buyer-tasks
page stub didn't include either field. As a result, the modal
showed 'Send' and an empty banner even when the underlying PO was
mail_failed. Now the stub includes both so the operator sees the
correct affordance.

Co-authored-by: Orca <help@stably.ai>

src/components/buyer-tasks/buyer-tasks-page.tsx

@@ -218,6 +218,8 @@ export function BuyerTasksPage() {
           purchaseOrder={{
             id: sendPoFor.purchaseOrderId ?? "",
             po_number: sendPoFor.poNumber ?? "",
+            status: sendPoFor.poStatus ?? undefined,
+            email_error: sendPoFor.emailError ?? undefined,
             expand: {
               supplier: {
                 email: sendPoFor.supplierEmail ?? "",